Quadruplex telegraphy.



I. KITSEE.

QUADRUPLEX TELEGRAPHY. APPLICATION FILED FEB. 25, 1915. RENEWED DEC. 30. 1916.

1,22%3U3o Patented Apr. 10, 1917.

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lUNllTE ICATE% P TENT OFFICE.

ISIDOR KITSEE, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO AMERICAN TELEPHONE AND TELEGRAPH COMPANY, OF NEW YORK,

N. Y., A CORPORATION OF NEW YORK.

QUADRUPLEX TELEGRAPHY.

Application filed February 25, 1915, Serial No. 10,520.

To all whom it may concern Be it known that I, lsinon Krrsnn, a resident of Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented a new and useful Improvement in Quadruplex Telegraphy, of which the following is a specification.

This invention relates to an improvement in quadruplex telegraphy and is specially applicable to a system of quadruplexing in which uni-directional pulses or current of one polarity denote one signal or message, in which uni-directional pulses or current of the opposite polarity denote a second signal or message, and in which pulses alternating in polarity, or an alternating current, denote the simultaneous transmission of two signals or messages.

I have discovered that on lines having considerable capacity, such for instance as copper lines most generally used today in telegraphic work, or lines on which telephone and telegraph are combined, or submarine cables, quadruplexing by means of a system which uses uni-directional pulses or current of one polarity to denote one message, uni-directional pulses or current of the opposite polarity to denote a second message, and alternating current or true reversals to denote two simultaneous messages, the presence of capacity greatly interferes with the proper working of the system, and if this capacity is above three microfarads signaling by means of such system becomes impossible.

I have found that if the capacity of the line exceeds in the neighborhood of three microfarads the absorption or losswith a uni-directional current or uni-directional pulses, is far less than the absorption or loss with alternating current or with pulses of alternating polarity, and that the greater the capacity of the line the greater is the diilerence between the losses or absorptions of these two currents.

The object of this invention is to obviate this difliculty and to enable the quadruplexing of lines with considerable capacity in systems of the character above specified.

Generally stated, the invention consists in a method of quadruplexing lines with capacity by impressing upon the line uni-directional pulses or current of one polarity Specification of Letters Patent.

Renewed December 30, 1916. Serial No. 139,971.

to denote one message, impressing upon the line uni-directional pulses or current of the opposite polarity to denote a second message, and impressing upon the line pulses of alternate polarity, or alternating current, to denote sinuiltaneously two messages, and doing this in a manner so that the difference in absorption or loss of the two kinds of current will not ait'ect the values of these currents at the receiving end, and result in the receipt of currents or pulses of substantially equal value in the receivin systems.

The accompanying drawings show a number of arrangements whereby this new method can be carried into effect, but without attempting to show all arrangements for accomplishing the purpose.

In the drawings Figures 1, 2 and 3 are diagrammatic views of three different a1' rangements of apparatus for carrying out the method.

Figs. 1 and 2 show transmitting systems in which 1 indicates the line, 1 and l branches thereof respectively for the two transmitting stations A and B. 2 and 2 indicate two sources of direct current, associated respectively with the two transmitting stations, and here shown as direct current generators, but, if desired, batteries may be used instead. 8 and 3 indicate two supplementary sources of direct current, here also shown as direct current generators. at indi "ates a rotating commutator bearing segmental contacts 5 and 5 with each of which cooperates a set of brushes, viz., brushes 6 and 7 cooperating with contact 5 and of which the former is connected to the positive pole of generator 2, and brushes 6* and 7 cooperating with contact 5 and of which the former is connected to the negative pole of generator 2 The opposite poles of generators 2 and 2 are grounded. 8 is a key or armature associated with station A, and 8 is a similar key or armature associated with station E. The key 8 cooperates with a stop 9 to which the line branch 1 is connected and the key 8 cooperates with a contact 9 to which the line branch 1 is connected. Both of these keys are biased, such as by springs 10 10, so that they are normally open at the line con tacts. Each of these keys carries a tail member, marked 11 and 11*, respectively,

' marked respectively 15-" and 15'.

which are insulated from the bodies of the keys and normally rest against stops 12 and 12 respectively. The tail member 11 is connected by wire 13 with the brush 7 and the tail member 11 connected by wire 13 with the brush 7. The positive pole of the supplemental generator 3 is connected through wire is to the body of key 8, and its negative pole to the brush 7 while the supplemental generator 3 has its negative pole connected through wire 14 to the body of the key 8", and its positive pole connected to the brush 7". In each of the circuit wires 14L and 14 is placed a small resistance coil The stop 12 is connected through wire 10' with the wire 14;", and the stop 12 is connected through wire 16 with the wire let.

If new when key 8 is open, the key 8 is depressed it makes contact with stop 9 and breaks contact between its tail piece 11 and stop 12. In this condition the positive pulses from generator 2 will flow through contact 5 on the rotating commutator 1 and brushesassociated therewith, through supplementary generator 3, wire 1-1, key 8, stop 9 line branch 1, to the line. The supplementary generator 3 is, however, short circuited through wires 14 16", stop 12, tail piece 11 and wire 13 so that only the energy from generator2 flows to the line. Negative pulses at this time cannot reach the line because the key 8 is opened at stop 9 If while the key 8 is opened the key 8 is depressed, so as to contact with the stop 9 the circuit is as follows: from the negative pole of generator 2 through contact 5 of the commutator 4:, through supplementary generator 3", wire 1 1 key 8", stop 9", line branch 1 to the line. The supplementary generator 3 is then short circuited through wire 14E, wire 153 stop 12, tail piece 11 and wire 13*, so that only the energy of generator 2 is impressed upon the line. Consequently, when sending a message only from station A, pulses of positive polarity are impressed upon the line and of a value equal to the voltage generated by generator 2; while in transmitting a message only from station B, negative pulses alone are impressed upon the line and of a value equal to the voltage generated by generator 2. If, however, both keys 8 and 8 are simultaneously depressed, the circuits from generators 2 and 2 respectively to the line are the same as before described, but the short circuits of supplemental generators 3 and 8 are both broken by the lifting of tail pieces 11 and 11 respectively from the stops 12 and 12'. Consequently, under such conditions pulses of alternate polarity are impressed upon the line, and these pulses will have a value of the voltages generated by the generators 2 and 2 respectively plus the voltages generated by the supplementary generators 3 and 3 respectively. Consequently, under this condition the alternating pulses impressed on the line have a higher value than the value of the positive and negative pulses when impressed upon the line. The result is that the greater losses or absorptions due to the capacity of the line when an alternating current or pulses of opposite polarity are impressed on the line is compensated for by the increased'value of the alv ternations impressed upon the line, so that the pulses or currents reaching the receiving instruments at the distant station are substantially equalized with those received at the receiving instruments when pulses of only one polarity are impressed upon the line. In this way lines of very considerable capacity can be practically quadriqiilexed. The value of the currents generated by supplemental generators 3 78* will be proportioned to the capacity of the line, in other words, the larger the capacity of the line, the greater must be the power of the supplementary generators.

When the line must be automatically grounded at both terminals, that is, when the terminals do not have a straight ground, I connect in the line, at each end, a relay comprising an armature 18 permanently connected to the line and arranged to cooperate with a pair of stops 19 and 20 respectively, the former of which is connected to ground 21 and the latter of which is connected to the line branches 1*, 1 The armature 18 is biased, such as by spring 22, so that normally it is in contact with the ground stop 19. Associated with this armature are a pair of magnet coils 23 and 23 the former of which is in a circuit 2%, in

which is a source of current 25, a magnet coil 26 associated with the key or armature 8, and a key 27 biased so as to normally hold the circuit 2 1 open. When key 27 is closed the magnet 26 is energized so as to draw key S into contact with stop 9 and the magnet 23 is also energized to draw the line armature 18 into contact with the stop 20. The magnet coil 23 is likewise in a local circuit 249 in which is a source ofcurrent 25, a magnet coil 26 associated with key 8 and a key 27 which is biased so that it nor mally holdsthe circuit 2 1 open. When the key 27 is closed it results in the energization of magnet 26 to draw key 8 into contact with stop 9 and also energizes magnet 23" to draw the line armature 18 into contact with stop 20. When this ground connection of the line is used the keys 27 and 27 become the operators keys, and the keys 8 and 8 are in effect relay armatures, as will pulses or currents when alternations are im- 1 37 for balancing purposes.

pressed upon the line, when both of the keys are simultaneously closed, the same general effect is produced by inserting resistances in the circuits of the primary generators when a single key is depressed, and providing means for automatically shunting such resistance through the depression of both keys, so that in effect the intensity or voltage of the uni-directional pulses is decreased below that of the alternate pulses or current. The circuit arrangements here employed differ from those shown in Fig. 1 only in substituting large resistances 30 and 30 in the same connections as the supplementary generators 3 and 3 of Fig. l, and in reversing the relation between the tail pieces 11 and 11 of the keys 8 and S with reference to the stops 1% and 12 that is to say, normally the circuits between these two tail pieces and stops are open, instead of being closed, as in Fig. 1. The result is that when only a single key is depressed the current from its associated generator 2 or 2" can reach the line only by flowing through the resistance 3O or 30, as the case may be, whereas, when both keys are simultaneously depressed both of the resistances 30 and 30 are short-circuited. When both keys are depressed the current from generator 2 passes from brush 7 through wire 13, tail piece 11", stop 12, wire 16*, to wire 1-1", and thence through key 8, stop 9*, line branch 1 to the line, while the pulses from generator 2* flow from brush 7 through wire 13 tail piece 11*, stop 1%, wire 16 to wire la and thence through key 8*, stop 9, line branch 1* to line, as before. This arrange ment has the same effect as in Fig. 1, via, to equalize the values of the received energy in the receiving instruments, so as to compensate for the greater loss or absorption due to the capacity of the line when the alternating current or pulses are impressed on the line.

Fig. 3 shows another arrangement for accomplishing the same result, this showing an arrangement at the receiving station. Here also 1 indicates the main line, 31 indicates the artificial line, and 33 the ground connection of the line. 34% and 35 indicate diagrammatically the relays of the receiving instruments. The remainder of the receiving circuits are not illustrated, as they will be readily understood by those skilled in the art. In the main line is inserted a large capacity, such as condenser 36, and shunted around this is a comparatively small variable resistance 37. In the artificial line is placed a similar capacity 36 and resistance The capacity 36 may have from 10 to 20 microfarads, more or less, depending upon the capacity of the line, and the resistance 87 may vary from 500 to 1000' ohms, more or less, depending upon the resistance of the line. With this arrangement when pulses of one polarity only arrive they cannot pass through the condenser 36, but must go through the resistance shunt, and will therefore be reduced in intensity, while when the pulses of alternating polarity, or an alternating current, arrive they pass through the condenser, as is well known, and encounter only slight resistance, so that they are substantially unreduced in intensity. By properly proportioning the value of the resistance 37 the pulses of one polarity can be reduced in intensity so that they will substantially equalize with the value of the pulses of opposite polarity, or alternating current, whose intensity has been reduced due to losses and absorption on the line to a greater extent than have the uni-directional pulses or current.

The method described is applicable not only to systems such as illustrated and described, that is, in which unidirectional pulses or current are impressed upon the line to indicate one message only, and pulses of opposite polarity, or alternating current impressed upon the line to indicate the tran smission of two messages simultaneously, but also to systems in which pulses of opposite polarity, or alternating current, are normally impressed on the line when no messages are being received, and the absence of all pulses on the line indicates the presence of two messages simultaneously, such as illustrated and described in my application, Serial No. 766,085, filed May 7, 1913.

The essential of the new method is the equalization of the values of the received pulses so as to compensate for the greater losses or absorptions on the line, due to the capacity of the latter, when alternations are being transmitted than when uni-directional pulses or current are transmitted. This, as will be noted, can be done either by inserting resistances at the sending station for decreasing the intensity or voltage of the unidirectional pulses or current and which resistances are automatically shunted when both keys are depressed to impress alternations on the line, as in Fig. 2, or by placing such a resistance in the line at the receiving end, shunted by a condenser so that the unidirectional pulses or current must flow through the resistance while the alternations pass through the condenser, as shown in Fig. 8, or by an arrangement for increasing the intensity or voltage of the alternations impressed upon the line when both keys are depressed, as shown in Fig. 1. In lieu of having booster or supplementary generators for securing this increase or intensity of voltage when both keys are depressed, as shown in Fig. 1, a step-up transformer can be substituted therefor, with the circuits so arranged that when only a single key is depressed the transformer is short-circuited, but when both keys are depressed, the transformer is put into the line circuit so as to increase the intensity or voltage flowing to the line.

Many other arrangements for securing the same results will readily suggest themselves to those skilled in the art.

What I claim is 1. The method of quadruplexing a line with capacity, which consists in impressing on the line uni-directional pulses or current to denote the transmission of a single message, impressing upon the line alternations to denote two simultaneous messages, and equalizing the values of the received pulses or current to compensate for the greater losses due to the line capacity when transmitting alternations.

2. The method of quadruplexinga line with capacity, which consists in impressing on the line at one time uni-directional pulses or current and at other times impressing on the line true alternations, and equalizing the intensity of the received pulses or current to compensate for the greater line losses when alternations are impressed on the line.

'3. The method of quadruplexing a line with capacity, which consists in at one time impressing upon the line uni-directional pulses or current and at other times impressing upon the line true alternations, and decreasing the intensity of the uni-directional pulses or current below the intensity of the alternations in order to equalize their values at the receiving station.

4. The method of quadruplexing a line with capacity, which consists in impressing upon the line at one time uni-directional pulses, or current and at other times true alternations, the alternations being of a higher value than the uni-directional pulses or current in order to equalize their value at the receiving station.

5. The method of quadruplexing a line with capacity, which consists in impressing upon the line uni-directional pulses of predetermined value to denote a single message, and impressing upon the line alternations of a higher value than the value of the unidirectional pulses to denote two simultaneous messages.

6. The method of quadruplexing a line with capacity, which consists in impressing upon the line pulses of one polarity and of predetermined value to denote one message, impressing upon the line pulses of opposite polarity and substantially the same predetermined value to denote a second message, and impressing upon the line alternations of a higher value than the value of pulses of single polarity to denote two simultaneous messages.

7. The method of quadruplexing a line with capacity, which consists in impressing upon the line pulses of one polarity to denote one message, impressing upon the line pulses of opposite polarity to denote a second message, impressing upon the line alternations to denote two simultaneous messages, and decreasing the intensity of the pulses of a single polarity below the intensity of the alternations inorder to equalize their values at the receiving station.

In testimony whereof, I have hereunto set my hand.

ISIDOR KITSEE. Witnesses:

GLENN H. LERESCHE, EMMA K. CUNNINGHAM.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. O. 

